Formation of Living Things—Experiment and Speculation

This volume presents the creative ideas and conclusions, inherently provisional, of one of Britain's most distinguished scientists and crystallographers on the origins of life. These ideas have their beginnings in his early contacts with Haldane, Oparin, and others, and have developed over a period of some thirty years. Professor Bernal, by his determinations of the structure of molecules of biological importance, and by the effect of his stimulating personality and example, has done much for molecular biology here and elsewhere. The study of the origin of life demands a sense of scientific history as well as an ability to weigh the evidence from widely different fields-geology and astrophysics, for example, as well as biochemistry and biology itself. Few if any at the present time could have presented the story so attractively and so well. When Pasteur performed his modification of the Spallanzini experiment over a century ago he purported to show that spontaneous generation of life was impossible; as Wald has pointed out, Pasteur simply showed that spontaneous generation was untenable under certain particular conditions. Conclusions about the origins of life depend on inferences from the probable history of the earth on the sequence of biologically significant events spaced over thousands of millions of years. Inevitably, even tentative conclusions must in part be based on informed, even inspired, speculation rather than the strict interplay of experiments and causes in the Baconian sense, on which so much of modern science depends. Important experiments, however, have been carried out, notably those of Urey and Miller on the formation of amino-acids by circulating a mixture of water vapour, methane, ammonia, and hydrogen over an electric spark. This experiment was in turn based on the Oparin-Haldane hypothesis that the early atmosphere of the earth was largely composed of hydrogen. Also inherent in the general approach is the supposition that the biochemical processes of life as we know it could not have arisen de novo; it is supposed that they were preceded by simpler and simpler processes. There now appears to be general agreement on the stages of the history of life on earth which may be summarized in the phrase: from atom to molecule, from molecule to polymer, from polymer to organism. Such words conceal the enormous amount of work and thought that has gone into the examination of how such processes could come about and lead to the formation of living things, and how the problems of deriving energy could be solved, and the atmosphere of the planet changed so that cellular respiration could take place. The problems of the origins of life are no longer confined to earth and there has been much speculation on the probability of its occurrence in other parts of the galaxy and elsewhere. These matters and many more are dealt with by Professor Bernal in this most attractive book and are balanced by serious consideration of the difficulties involved. Notable features which contribute to the overall synthesis are the illustrations accompanying the chapter entitled "From Molecule to Cell"; the appendices in which the dassic contributions of Oparins, Haldane, and Mueller are brought together; the glossary, which helps the less well-informed; and the bibliography to draw us on to further reading. J. T. RANDALL.